A Generalization to Signed Graphs of a Theorem of Sergey Norin and Robin Thomas

Abstract

In this thesis we characterize the minimal non-planar extensions of a signed graph. We consider the following question: Given a subdivision of a planar signed graph (G, Σ), what are the minimal structures that can be added to the subdivision to make it non-planar? Sergey Norin and Robin Thomas answered this question for unsigned graphs, assuming almost 4-connectivity for G and H. By adapting their proof to signed graphs, we prove a generalization of their result.